Article Figures & Data

Figures

Shaded relief representation of the DEM (100 m resolution) of Sunda Strait, based on ASTER topography, GEBCO bathymetry and a digitization of the bathymetric map of Krakatau from Deplus et al. (1995, their fig. 7). This DEM is the calculation grid used to simulate the Anak Krakatau landslide and the subsequent tsunami propagation (calculations were made at a resolution of 200 m). The main coastal cities or important infrastructures around the Sunda Strait are indicated by red diamonds. The black frame around the Krakatau Archipelago corresponds to the limits of Figure 2b, c. Geographical co-ordinates are in metres.

(a) Cross-section of Anak Krakatau (inset: Fig. 1) and the 1883 eruption caldera. The landslide scar, defined by modifying some level lines on our initial DEM, is drawn in black. It is orientated southwestwards, with a slope of 8.2°, delimiting a collapsing volume of about 0.28 km3. (b) Topography before the simulated landslide, with the location of the cross-section presented in (a). The caldera resulting from the 1883 Krakatau eruption is clearly visible, as well as Anak Krakatau, which is built on the NE flank of this caldera. (c) Topography after the simulated landslide, with the horseshoe-shaped scar clearly visible.

(a) Simulated debris avalanche deposits obtained using rheologies 1–2 (grey) and 3–4 (black hatching and black) to simulate the landslide propagation. (b) Simulated water surface displacement recorded at the gauge located in Figure 2a (black diamond). This figure shows that the waves produced are very similar, whatever the rheology used to simulate the landslide propagation.

First wave travel time (expressed in min) for the first 90 min of simulation. Black lines are at 2 min intervals. Main coastal cities (names in Fig. 1) are shown by red diamonds. The impact of the sudden increase in water depth westwards from the Krakatau Archipelago is clearly seen (see Fig. 1 for bathymetry), the waves being more rapid than those crossing the shallow strait. BL, Bandar Lampung; K, Kalianda; M, Merak; A, Anyer; C, Carita; L, Labuhan; P, Panimbang. The simulation of the landslide propagation was carried out using a constant retarding stress of 10 kPa.

Simulated sea-level profiles (m) registered several hundred metres (indicated on the plots) off eight of the main coastal cities located in Figure 1. The simulation of the landslide propagation was carried out using a constant retarding stress of 10 kPa. Time is expressed in seconds after the collapse onset. The water depth below each gauge is indicated in Table 1.